I wonder if the "12 Days of Bitcoin" on Bloomberg played a tiny part in this. I was watching a segment the other day which had one of the reporters talk about purchasing BTC and mention that Coinbase is very reputable.
Doubtful, I think. Raising venture rounds of any size (especially this one) takes a very long time! Bloomberg may have caught wind of the deal, however, and chose to release the story to capitalize on the press trend.
http://www.bloomberg.com/video/12-days-of-bitcoin-what-do-yo...